WO2009038466A1

WO2009038466A1 - Encapsulated and modular gear system

Info

Publication number: WO2009038466A1
Application number: PCT/NO2008/000265
Authority: WO
Inventors: Christian Antal; Knut Tore Ljosne
Original assignee: Christian Antal; Knut Tore Ljosne
Priority date: 2007-07-13
Filing date: 2008-07-14
Publication date: 2009-03-26
Also published as: NO20073623L

Abstract

The present invention considers a gear system (100) for a bicycle or like, where the gear system comprises an epicyclic gearing having planet pinions (15), a sun pinion (5) and a outer gear (14). The sun pinions are mounted in a rotating holder (20). The epicyclic gear has a housing (19) which encloses the epicyclic gearing. The housing (19) is separate from the hub with its shell, spoke holes and axle. The housing (19) has a straight-through hole (26).Therefore the housing (1 9) can be mounted or disconnected from the hub without breaking the housing which encloses the epicyclic gearing. This housing can be mounted on a derailleur-wheel set in stead of the sprocket wheel rings.

Description

Encapsulated and modular gear system

The invention according to the present application concerns an encapsulated and modular gear system for bicycles, which can be mounted on and separated from a hub on the bicycle, with its spoke fastenings and rim ring, without breaking the encapsulation of the gear system or exposing the inner gear mechanisms. More specifically, the invention concerns a gear system which is mounted on the rear wheel of a bicycle by means of splines, threads or other mechanical couplings, where the gear system comprises an encapsulated planetary gear, a chain adjuster, which takes up slack in the bicycle chain, and a torque-transmitting arm attached to the bicycle's chain stay on the frame.

The gear system is crucial for the function of today's bicycles. A gear system allows the rider to switch gear ratios and hence choose an appropriate cadence (pedal frequency) given variations in speed, terrain and elevation. When the bicycle moves uphill or off-road, the rider will have to perform greater amounts of work in order to maintain or increase the speed. If the hill becomes too steep or the terrain too difficult, the rider will not manage to maintain the same pedal frequency as he would with the same effort on a gentler slope or on a level surface. Being able to shift to a lower gear, with a higher gear ratio, makes it possible for the rider to maintain a high enough pedal frequency to be able to maintain the momentum despite the changes in the terrain. Correspondingly, when the bicycle moves downhill or on a more level surface, the rider will need to work less in order to increase or maintain his speed. If the speed becomes too high, the rider will not be able to maintain a sufficiently high pedal frequency to supply power to the rear wheel. Being able to shift to a higher gear, with a lower gear ratio, will make it possible for the rider to supply power in spite of the changes in the terrain.

The majority of today's mountain bikes and road bikes use derailleur gear systems, with 27 gears and 20 gears respectively, and a range in gear ratio of ~4 and ~3,5 times. Such gear systems consist of open mechanisms, a front gear and a rear gear that lift or push a chain over from one sprocket to another sprocket, thereby changing the gear ratio between the pedals and the rear wheel. At the front of the crank there may be one, two or three sprockets, while on the rear hub there are usually up to ten chain wheels in a gear rim, often assembled into one integrated chain wheel cassette. Thus in simple terms, the hub consists of a hub shell attached to the wheel's external wheel rim with tyre by a set of spokes mounted in a given spoke pattern, an axle which passes laterally through the wheel, so that the wheel can be slid into fastenings in the bicycle's frame and secured, and ball bearings which enable the hub shell to rotate relatively friction-free relative to the axle and the frame, which remains stationary relative to the wheel's rotating motion. In the bicycle's rear wheel there may be a freewheel coupling that enables the chain wheel cassette to rotate in the opposite direction to the direction of travel, independently of the wheel, but not in the direction of travel. This has two important purposes: to enable forces from the pedals to be transmitted to the rear wheel when the rider pedals and exerts force on the pedals, and to enable the rear wheel to rotate at higher speed than the pedals when the bicycle is moving. The gear rim can usually be detached from the rear hub, so that the gear rim is mounted on the rear hub when in use and can easily be detached and replaced when worn or if it fails. There are basically two different hub- and gear rim standards. On hubs with an integrated freewheel, freewheel hubs, the freewheel coupling mechanism is integrated with the hub and typically designed so that a chain wheel cassette is slid on to the hub splines and locked on to the hub with a simple locking ring. On fixed hubs, on the other hand, the freewheel function is integrated with the gear rim in another kind of chain wheel cassette. This cassette, which in this case is called a freewheel, usually has threads on the inside and is mounted by being screwed to the hub. This solution requires the complete freewheel with gear rim and freewheel coupling mechanism to be replaced when the sprockets are worn. Within these two main categories there are many other different standards that use different splines or thread patterns and are therefore not compatible.

Derailleur gear systems are simple, light and cheap to produce. However, they are not encapsulated and the mechanism is therefore exposed to foreign elements which can damage functionality and/or increase the risk of sudden failure. They are furthermore more exposed to impact, shocks and shaking, require a great deal of maintenance and fine adjustment, and are not user-friendly since they have a front gear and a rear gear that have to be coordinated. In general, derailleur gear systems are weak, unreliable, sensitive to wear and primitive in comparison with gear systems on machines with which it is natural to compare them, such as, for instance, light vehicles, motorbikes, mopeds, motorised lawnmowers, or radio-controlled cars and planes.

In contrast to derailleur gear systems we have hub gear systems, which are more reliable, robust and user-friendly types of gear system for bicycles. The most common hub gear systems consist of specially developed planetary gears, which are integrated with the hub on the rear wheel on the bicycle, and which therefore cannot be removed from the rear hub, moved to another bicycle wheel or replaced without considerable effort.

A planetary gear consists of one or more planet wheels, which rotate between a central sprocket/sun wheel and a ring wheel/annulus, and is typically mounted to a rotating holder, the planet holder, which can rotate relative to the sun wheel and annulus. By locking or connecting these elements, several gear ratios are available, and by combining several such planetary gears in series, a large number of gear ratio alternatives may be obtained from one single system. Good functioning of such a planetary gear is dependent upon critical individual components such as sprockets and bearings in the planetary gear working well with a good fit, minimal friction and resistance. These components must therefore be machined to very close tolerances, often be run in over a period of time in order to mesh well, and furthermore be well lubricated, and possibly continuously lubricated from grease or oil stores in the gear system. Even small impurities in the form of grains of sand, dirt, or the like can lock the mechanism and as an extreme consequence cause critical damage to the sensitive parts. This is particularly problematic when using mountain bikes, whose intended use is precisely in environments where such contamination is common. To protect the inner mechanisms against potentially harmful external influence, these planetary gears are therefore usually fully encapsulated and sealed, and it is not possible to gain access to and expose the inner mechanisms without a major operation, such as, for instance, service in a workshop. Usually it is not possible to replace individual components from the planetary gear in the case of, for example, failure or wear. In this case, the entire gear must be replaced. This is compensated by the fact that planetary gear systems are often more hardwearing, reliable and resistant to external influences than derailleur gear systems. There are also other types of hub gears, for instance hub gears based on so-called CVT technology. Such gear systems are integrated in the bicycle hub in a similar fashion to planetary gears in planetary gear hubs.

Cyclists often use several complete sets of wheels, for example with various types of rims and tyres, for use under different conditions. In competition situations, riders will also wish to have the possibility of quickly switching to another set of wheels, for example, in case something unexpected happens to the wheels that are currently on the bicycle. Wheels on bikes with quick release mechanisms are easy to remove from and mount on to the bicycle, while wheels that are screwed on to or fixed to the bicycle often require the use of tools in order to be removed from the bicycle. If the wheel has to be replaced on a bicycle that has a derailleur gear system, the shift mechanisms or gear arms are left attached to the bicycle while the chain wheel cassette is removed from the bicycle along with the wheel. Chain wheel cassettes are relatively cheap, thereby permitting one separate cassette to be mounted on each wheel, and a quick wheel change to be carried out. With this method, however, there will often be a need to adjust the gear. As an alternative, the cassette may be removed from the old wheel and mounted on the new wheel, thereby providing uniform wear on gear rim and chain. This is possible due to the fact that, amongst other things, present day standards for derailleur gear systems are such that the chain wheel cassette is usually easy to mount on to and remove from the hub. On bicycles with hub gear, i.e. on all bicycles with planetary gears on the market today, the process of changing wheels is different, as the gear system is integrated in the hub and cannot be removed from the wheel for mounting on another wheel without loosening all the spokes from the wheel rim, reattaching them to another wheel rim and adjusting them properly, in other words a major operation. Several sets of complete gears, one for each rear wheel, are therefore required if one wishes to have the capability of shifting wheels easily on the bicycle. At the same time, hub gears are often expensive to purchase compared to derailleur gear systems, since the complexity and precision of the many inner mechanisms result in high production costs.

An object of the present invention will therefore be to provide a gear system for bicycles, which like known hub gears consists of, for instance, a planetary gear, and which furthermore is encapsulated in a housing, container or the like, which is resistant to shocks, impact and foreign elements, is reliable over time and requires a minimum of maintenance and adjustments in typical extreme situations where such bicycles are used, offers the possibility of replacement or repair of individual components in the planetary gear in the event of, for instance, failure or wear, can easily be adapted by the rider in order to obtain the desired loads and/or gear ratio given the terrain, and is furthermore more advantageous to use in other ways in comparison with derailleur gear systems.

Another object of the present invention is to provide a gear system which in contrast to hub gears is simultaneously compatible with a great number of today's bikes, wheels and hubs, for example due to the fact that the gear system can be mounted on hubs intended for use with the dominant standard for bicycles today, derailleur gear systems, thus enabling the encapsulated gear system to easily replace these derailleur gears, and be easily attached to and removed from a bicycle wheel, without the inner mechanisms in the gear system being exposed and subjected to potentially harmful effects from foreign elements.

In a first aspect of the invention, a gear system for a bicycle is provided, wherein the gear system comprises a planetary gear with one or more planet wheels, a central sun wheel and a ring wheel mounted on to a rotating holder. In order to avoid impact and/or shocks to the various components, the planetary gear, moreover, is encapsulated in a housing, container or the like, separately from the hub shell with its spoke fastenings and wheel rim. By encapsulating the planetary gear as a separate unit, the object is simultaneously achieved that the gear system can be easily and completely attached to and detached from a bicycle's rear wheel without exposing the unit's inner mechanisms in such an operation. The two separate units, the encapsulated planetary gear with its internal gear mechanisms and the hub with its hub shell and spoke fastenings may nevertheless be easily assembled to form one functional unit, and easily separated again to form two separate encapsulated units.

The actual encapsulation of the planetary gear may be envisaged designed in many ways. Its shape may be circular, square or another suitable shape, where the actual housing or container may be composed of two identical hollow halves, between which the planetary gear's components are arranged. The halves are assembled and screwed together by means of, for instance, bolts, screws or the like. Another possibility is that the halves are attached to each other by clips, glued together etc. The encapsulation may also be composed of a lidded container. Most preferred is a whole encapsulation, i.e. the sensitive parts of the planetary gear are completely encapsulated and protected, but the encapsulation may also be made partly open.

Inside the housing or the container of the planetary gear, a system may be provided to ensure oil or grease lubrication of the inner mechanisms, for instance a chamber, where this is designed so that one or more of the planetary gear's inner components will come in contact with this chamber. Furthermore, devices may also be provided in the housing or the container for securing one or more of the planetary gear's components, where the components may either be secured by screws, snapped into place or attached in another suitable manner. The housing or the container encapsulating the planetary gear may be provided at its centre with a through-going hole, where the inside of the hole is shaped complementarily to the hub's splines, for attachment thereto.

The encapsulated planetary gear may have from one up to several series of planetary gears, whereof each series theoretically can give up to three gear ratios. More series offers the possibility of having more gear ratio alternatives. Different elements of the planetary gear - the sun wheel, the planets or the annulus - may be connected as input (driving) or output (driven) gears.

The encapsulated planetary gear may furthermore have from one up to several tens of different gear ratio alternatives, depending on how the planetary gear is designed, the number of series it consists of, and which locking mechanisms are employed. The more individual gears the system has, the more alternative pedal frequencies the rider can select.

Depending on the size of the sprockets employed, the encapsulated planetary gear may offer different ranges in gear ratios for different use. For instance, a gear system for use on road bikes will have a different range in the gear ratios compared to a gear system for mountain bikes. A large range will give the rider gear ratio alternatives that suit a wider speed interval, while a smaller range will give the rider gear ratio alternatives that suit a narrower speed interval. The smaller the range between the gear ratios, the less difference there will be in the pedal frequency at the same speed in the various gear ratios, and conversely, the wider the range, the greater the difference will be between the pedal frequency at the same speed in the various gear ratios.

Since the encapsulated planetary gear is not meant to be opened for normal daily maintenance, lubrication is provided in the actual housing or container for one or more of the planetary gear's components. This may be, for example, a chamber containing either oil or grease, where one or more of the components in the planetary gear are entirely or partially in contact with this chamber. There may also be a shut-off port or drain plug in the housing or the container, which permits old grease or oil to be drained off and refilling with new grease or oil. Power transmission to the wheel is such that the encapsulated planetary gear's input train will be on the outside of the encapsulation, and the output train will be on the rotating inner holder, corresponding, for example, to the manner in which a chain wheel cassette is driven by a chain, with a chain which is pulled around on a chain wheel by crank arms, and which furthermore drives the gear rim on the rear wheel round while the chain moves almost parallel to an actual or imaginary chain stay, forwards on the top and backwards on the bottom of this chain stay.

The encapsulated planetary gear will be able to be made available for use on all types and standards of hubs that are adapted for derailleur gears and gear rims. This is achieved by employing an attachment mechanism in order to mount the encapsulated planetary gear, where this attachment mechanism secures the planetary gear to a hub. Thus the attachment mechanism is a separate part of the gear system and may therefore be manufactured to be able to fit the different types of hub. In its simplest form the attachment mechanism may be a sleeve, the surface of which sleeve is designed so as to be attached to the encapsulated planetary gear's housing or container. The surface of the sleeve may then be provided with notches, grooves or the like round its own perimeter (i.e. transversally to the sleeve's longitudinal direction), whereby complementary notches, grooves or the like in the housing's or the container's through-going hole will ensure a secure attachment of the housing and the sleeve. Since the inside of the sleeve is furthermore provided with notches, grooves or the like, the encapsulated planetary gear with the sleeve may be slid on to complementarily shaped grooves on a hub, thereby securing the planetary gear. It should be understood that the attachment mechanism may also have other shapes, for instance square, polygonal, oval, etc. The attachment mechanism may furthermore be made of a material that is light but at the same time resistant to large loads, weather etc. Such materials may be composites, various metals or alloys, where this will be well-known to a person skilled in the art.

An encapsulated planetary gear with a sleeve, manufactured for one type of attachment standard, will possibly - but not necessarily - be able to be used on a hub which basically uses another attachment standard, depending on how great the difference is between the two standards. Alternatively, the encapsulated planetary gear will be able to be constructed around other types of hub standards than those in general use today. The attachment mechanisms might therefore differ from those normally in use today, with, for example, different types of splines, threads or other types of attachment mechanisms, such as spring-loaded or magnetic attachment mechanisms. Other alternatives involve, for example, making the outer diameter of the hub's attachment area smaller, so that the inner diameter on the encapsulated planetary gear may correspondingly be made smaller, and that the hub's freewheel mechanism and the planetary gear's freewheel mechanism may be incorporated in the actual housing.

The gear system may also include a chain adjuster integrated with the encapsulated planetary gear in order to compensate for the initial slack in the chain and/or for variation in the chain length if the bicycle is equipped with rear wheel suspension.

A torque-transmitting arm may furthermore be integrated with the encapsulated planetary gear. The arm is spring-loaded against the bicycle frame, and the part that is in contact with the frame has a universal plate with a bend so that it can be adjusted to various chain stay configurations.

A chain wheel is mounted to the encapsulated planetary gear, where this is achieved by means of fastening mechanisms, such as bolts etc, used to bolt together the housing or container. The chain wheel can alternatively be attached by use of dedicated means to the housing or container.

The wire attachment may be designed so that it is easy to loosen the wire from the gear system, in order to further facilitate removal of the wheel and the encapsulated planetary gear should maintenance and/or replacement of components become necessary.

For mounting the encapsulated planetary gear on a freewheel hub, there will be splines on the encapsulated planetary gear corresponding to splines on the chain wheel cassette for this type of freewheel hub, thereby permitting the encapsulated planetary gear to be slid on to the freewheel hub, and possibly secured by screws in the same fashion as a chain wheel cassette would be mounted and screwed on. If the pattern of the splines is sufficiently similar, the same"gearbox" could be used on hubs with different spline standards. For mounting the encapsulated planetary gear on a fixed hub, the freewheel coupling will be able to be located in the actual encapsulated planetary gear, and threads on the encapsulated planetary gear will enable this to be mounted in the same fashion as a freewheel is mounted on the hub.

In an embodiment, the encapsulated planetary gear consists of three planet sections mounted in series. In this case the gear changes will be performed by locking each of the sun wheels relative to the non-rotating axle or to the ring wheel (annulus). The three sections work the same way, with input rotation on the planet holder and with output rotation on the ring wheel. In a locked position, the sun wheel in one section will be locked relative to the central, non-rotating axle by means of a cam- operated pawl. The section therefore has higher output revolutions than input revolutions with a gear ratio determined by the number of teeth on the sun wheel, the planets and the ring wheel. When the sun wheel is unlocked, it will try to rotate in the same direction as the planet holder and the ring wheel. Friction-operated pawls then automatically lock the planet holder relative to the ring wheel, and the section rotates in unison, giving a 1:1 gear ratio. The section that runs on the lowest gear ratio has double planet wheels, where the largest planet wheel is in contact with the sun wheel and the smallest planet wheel is in contact with the ring wheel. Friction-operated pawls are located so that they are activated or deactivated by the relative motion between the sun wheels and the planet holder to which they are attached. This is implemented by the spring-loaded part of the pawl mechanism having frictional contact with the sun wheel, and rotating around a fulcrum into or out of engagement with a toothed ring mounted on the ring wheel. The pawls are thereby retracted during rotation in a non-locking direction, in order to reduce wear and noise.

Gear shift is implemented by means of a rotating cam which has three different cam sections and operates locking pawls which lock the rotation of the sun wheels relative to the non-rotating central axle. The shift cam is rotated by a wire and has a spring return mechanism. The surfaces of the three cams are positioned so that there is one cam on the outside and two on the inside, where in a preferred embodiment these are located at 120° relative to one another. Other configurations and/or designs of cam or cam sections will also be possible, and these will be well known to those skilled in the art.

The gear ratios on the gear are determined by the combination of the three sections, giving a total gear ratio range of 3.5, corresponding to approximately 80 percent of the gear ratio range of a standard 27-gear derailleur gear system. The gears are distributed so that there are six gears in the middle of the interval, for smaller intervals between these gears than between each of the two gears at the outer edge. This gives the cyclist six gears in which to adjust the gear train under normal conditions, and two gears for more extreme conditions when climbing uphill or travelling downhill. The size of the crank sprocket is determined by the use of the bicycle. For instance, a rider will choose a sprocket with 44 or 46 teeth for downhill cycling, while a sprocket with 32 teeth will be more ideal for technical trail cycling.

The encapsulated planetary gear is driven by the bicycle's pedals via a power transmission from the pedals and the crank. The encapsulated planetary gear's function does not depend on the type of power transmission from pedals to the encapsulated planetary gear. It may be driven, for example, from the pedals via a chain, a belt, a cardan rod, by hydraulic transmission or by another kind of power transmission. When using a chain or belt, a chain wheel attached to the crank arm will rotate when the pedals are turned by the cyclist, driving a chain which drives another chain wheel on the outside of the encapsulated planetary gear, in a similar manner to how a gear rim is driven.

The encapsulated planetary gear may have a mechanically operated manual gearing, for instance hydraulically or by wire, via a shifter placed on the bicycle's handlebars or frame, or an electric or other type of shift mechanism/switch. In the future it will also be possible to offer an encapsulated planetary gear controlled by a processor which calculates speed, elevation, moments, RPM and pulse level, and which on the basis of one or more of these parameters places the system in a suitable gear.

For the manufacture of the encapsulated planetary gear it will be possible to employ traditional materials like steel, aluminium or plastics, or also more exotic materials such as carbon fibre, titanium as well as other materials. An important point, however, will be that the housing or the container should have a low weight and moreover be resistant to impact, loads and weather.

Alternatively, it will also be possible to combine the encapsulated planetary gear with other gear systems of various types and numbers of gears. The combination of a 3-stage front gear and an 8-speed gearbox will, for example, give a total of 24 gear ratios, while the combination of a 2-stage front gear and a 16-speed gearbox will give 32 gear ratios.

An example of a preferred embodiment will now be described, with reference to the attached drawings, in which: Figure 1 shows an expanded planetary gear according to the present invention, illustrating the planetary gear's construction and various main elements,

Figure 2 shows an external planet section of the planetary gear, where a shift cam is in a locked position,

Figure 3 shows the same planet section in the planetary gear as illustrated in figure 2, but here the shift cam is rotated so that locking pawls are released from the sun wheel,

Figure 4 correspondingly illustrates an innermost planet section of the planetary gear, when the friction-based locking mechanisms are rotated and a planet holder is released from an outer ring, Figure 5 shows the same planet section in a position where the friction-based locking mechanisms are fully engaged with the outer ring, Figure 6 shows three planet sections and the main components therein,

Figure 7 shows a complete encapsulated planetary gear according to the present invention, and

Figure 8 shows the same encapsulated planetary gear as illustrated in figure 7, but mounted on a bicycle.

Figure 1 shows an expanded planetary gear 100 according to the present invention, illustrating the construction of the planetary gear 100 and the various main elements. The planetary gear 100 comprises three planet sections 22, 23, 24, where these are arranged round a central non-rotating shift mechanism 1. Each planet section 22, 23, 24 is further composed of a planet holder 2, 3, 4, where these planet holders comprise a planet wheel 15, a ring wheel 14, a locking ring 18 and locking pawls 11, 17. A more detailed description of the planet sections' 22, 23, 24 construction and mode of operation will be given in figure 6. A first planet section's 22 planet holder 2, which forms the input unit in the planetary gear 100, is integrated in or attached to an element which forms a half of a housing or a container 19. To the outside of this housing or container 19 a chain wheel 7 may be attached. Inside the planet holder 2, furthermore, the central, non-rotating shift mechanism 1 is mounted, consisting of a shift cam 13, locking pawls 11, 17, the external bearing and needle bearing (not shown). A central planet holder 3 is mounted inside the planet holder 2 and the central non-rotating shift mechanism 1, and in a similar manner to the first planet holder 2, it comprises a planet wheel 15, a ring wheel 14, a locking ring 18 and locking pawls 11, 17. A third planet holder 4 is mounted inside the central planet holder 3 and it comprises double planet wheels 15, a ring wheel 14, a locking ring 18 and locking pawls 11, 17. If the side of the housing or the container 19, on which the chain wheel 7 is mounted, is the external side of the planetary gear, the third planet holder 4 will be the innermost planet holder. Inside the third planet holder 4 a sun wheel 5 is mounted, where this is integrated with or attached to a second half of a housing or a container 19. When the described components are assembled, the two halves of the housing or the container 19 will enclose them, forming an encapsulated planetary gear 100. The housing or the container 19 is provided with a through-going hole 26 in the centre, in which hole 26 a sleeve 20 is arranged. The internal circumference of the through- going hole 26 is provided with grooves which are complementary to grooves arranged on the sleeve's 20 external circumference, with the result that the housing or the container 19 will be attached to the sleeve 20 in a secure manner. The sleeve 20 is furthermore provided internally with splines, whereby the encapsulated planetary gear 100 with the sleeve can be mounted on a hub located on the bicycle's rear wheel. When the two halves forming the housing or the container 19 are then assembled, they will be screwed together by means of bolts 8. The bolts 8 are also employed to secure the chain wheel 7 to the housing or the outside of the container 19. In addition the encapsulated planetary gear 100 comprises a lever arm 9 and a chain adjuster 10 which are also mounted on the outside of the encapsulated planetary gear.

The planetary gear is built up round three planet sections 22, 23, 24, as illustrated in figure 6, by means of several large subassemblies in order to facilitate production and the assembly of the planetary gear. Each of the three planet sections 22, 23, 24 is produced as a separate unit, where each planet section 22, 23, 24 includes a planet holder 2, 3, 4, planet wheel 15, 21, sun wheel 5, friction-driven locking pawls 17 with respective axles and bearings (not shown), and locking ring 18. In the assembly of the planetary gear, planet holder 2, 3, 4 with respective planet wheels 15, 21 is combined with the preceding sections' 22, 23, 24 ring wheel 14 and locking ring 18 to form a combined holder unit: planet wheel-/ ring wheel-/ locking ring holder. The sun wheels 5 are associated with a subassembly of the central axle with the non-rotating shift mechanism 1. The operational function is similar for the three planet sections 22, 23, 24. The function of the locking pawls 11 for the sun wheel 5 is different for the outermost planet section 24 and for the two innermost planet sections 22, 23 (the outermost is shown). The use of locking pawls 17 operated by the rotation in order to lock the locking ring 18 and thereby the ring wheel 14 is similar. The innermost planet section 22 has double planets 21, which reduce the gear ratio when respective sun wheels 5 are locked, but the general function is similar to that of the other sections 23, 24.

Input on each planet section 22, 23, 24 is the planet holder 2, 3, 4. Each section 22, 23, 24 has two states: the section connected internally (planet holder 2, 3, 4, sun wheel 5, 21 and ring wheel 14 rotate together), giving 1:1 gear ratio, and sun wheel 5 locked externally, where gear ratio is determined by the number of teeth on the sun wheel 5 and the ring wheel 14 for respective planet sections 22, 23, 24, see for example figure 2. In the latter situation the planet wheels 15, 21 and the planet holder 2, 3, 4 (input) will rotate in the direction of the arrow r, while the sun wheel 5 is locked by locking pawls 11, activated by a spring 12 when shift cam 13 is in locking position. The ring wheel 14 (output) then rotates R in the same direction as the planet holder 3, with a higher rotational speed.

Figure 3 shows the shift cam 13 rotated so that the locking pawls 11 are released from the sun wheel 5, and the latter attempts to rotate in the direction of the arrow r, in the same direction that the planets 15/the planet holder rotates R, and the torque is therefore not transmitted to the ring wheel 14.

Figure 4 shows when the sun wheel 5 rotates in the direction of the arrow r and the friction-operated locking pawls 17 are rotated in a direction O round their axle A positioned by the planet holder, by means of a contact friction F that is produced between the spring-loaded part of the locking pawl 17 and the cylindrical surface of the sun wheel 5. The locking pawl 17 will be engaged with a locking ring 18, which is connected to the ring wheel 14, thereby acting as the section's output.

In figure 5 the locking pawls 17 are fully engaged K with the locking ring 18 which is connected to the ring wheel 14 and the locking ring 18 rotates r in the same direction and with the same rotational speed as the section's input, the planet holder, and the sun wheel 5. The section is now interconnected and running in 1:1 gear ratio.

Figure 6 shows the main components in the three planet sections 22, 23, 24, the single planets 15 and the double planets 21, the ring wheels 14, the locking rings 18 with their respective, friction-operated locking pawls 17, and the internal sleeve 20 with internally disposed grooves, where these grooves are complementary to the splines on the bicycle wheel's hub for connection to this hub.

In figure 7 the expanded planetary gear's 100 elements are, as illustrated in figure 1, assembled to form an encapsulated planetary gear 100. The chain wheel 7 is attached by means of bolts 8 to a housing or a container 19 which form the encapsulation of the planetary gear. The housing or the container 19 consists of two halves, where the two halves are interconnected by means of the bolts 8. The chain wheel 7 is also attached to the encapsulated planetary gear 100 by means of the same bolts 8. When the encapsulation 19 is screwed together, the lever arm 9 and the chain adjuster 10 will also be able to be attached to the encapsulated planetary gear 100. The lever arm 9, with the mounted chain adjuster 10, is mounted on the central, non-rotating shift mechanism 1. The chain wheel 7 can in an alternative embodiment be joined to the housing or container 19 through dedicated means. The encapsulated and modular gear system is illustrated in figure 8, where, together with the lever arm 9 and the chain adjuster 10, it is securely mounted on the rear wheel of a bicycle. The gear system, furthermore, is connected in a known manner with a bicycle chain 25, where the bicycle chain 25 is placed over the chain wheel 7 and on over the chain adjuster 10. The invention has now been explained by means of a non-limiting embodiment. A person skilled in the art will appreciate that it will be possible to implement a number of variations and modifications of the gear system as described within the scope of the invention as it is defined in the accompanying claims.

Claims

1. A gear system for a bicycle or the like, comprising a planetary gear (100) with one or more planet wheels (15, 21), central sun wheels (5), ring wheels (14), and with one or more rotating holders (2, 3, 4), characterised in that the planetary gear (100) is encapsulated in a housing (19) separate from the wheel hub with its sleeve, spoke fastenings and axle, thereby enabling the complete planetary gear to be attached to and removed from the hub without the housing (19) encapsulating the planetary gear (100) being broken.

2. A gear system according to claim 1, characterised in that the encapsulated planetary gear (100) is attached to the bicycle's rear wheel by means of mechanical couplings.

3. A gear system according to claim 1, characterised in that the encapsulated planetary gear (100) comprises at least one gear ratio alternative.

4. A gear system according to claim 1, characterised in that the encapsulated planetary gear (100) comprises at least one planet section (22, 23, 24).

5. A gear system according to claim 1, characterised in that the encapsulated planetary gear (100) is driven by mechanical transmission mechanisms.

6. A gear system according to claim 1, characterised in that it further comprises a lever arm (9) and a chain adjuster (10).

7. A gear system according to claim 1, characterised in that in the housing (19) there is provided a chamber for holding lubricants such as oil or grease.

8. A gear system according to claim 7, characterised in that in the housing (19) there is further provided a drain plug for the lubricants.

9. A gear system according to claim 1 or 2, characterised in that a sleeve (20) is provided internally with at least one spline.